1. Field of the Invention
The present invention relates to the field of multistage turbo-compressors, and more particularly, to a portable turbo-compressor which supplies pressurized air to a paint spray system or the like.
2. Background Art
Industrial spray painting systems are commercially available, wherein a turbo-compressor and drive motor are mounted on a cart and transported as a unit to the article to be painted. In these units, the motor and the turbo-compressor are mounted adjacent to each other upon a horizontal plate which constitutes the cart.
One of these units is described in U.S. patent application Ser. No. #067,305 entitled "Turbo-Compressor Havisng Air-Cooled Bearing", by Dennis W. Toth, which was filed on June 27, 1987, and which is incorporated by reference herein. The motor shaft and turbine shaft extend vertically downward through their respective housings and the mounting plate, and are coupled to each other by a drive belt located below the mounting plate. The electric drive-motor is mounted with the drive shaft disposed vertically and projecting downwardly through an opening in the housing. Rotation of the shaft of the drive motor is transmitted to the shaft of the turbo-compressor by an encased belt and a pulley drive. The turbo-compressor has multiple stages with the final stage being located at the bottom of the compressor. The chamber which encloses the final stage is defined by the bottom of the compressor housing, through which the drive shaft extends. The high speed rotation of the drive shaft causes a continuous and relatively high rate of flow compressed air from the final stage of the turbo-compressor.
There is a continuous and high rate of compressed air flowing through a restricted orifice opening into the chamber below the mounting place. The high speed rotation of the drive shaft does not tightly seal this opening, but this air flow generates a high noise level. Additional noise is generated at the intake to the turbo-compressor. U.S. Pat. #4,729,722 entitled "Noise Suppressor for Turbo-Compressor" by Dennis W. Toth, which is incorporated by reference herein, describes an apparatus for suppressing this noise.